Preliminary sedimentary OM and IM results

1. Import cleaned .csv file and look at dataframe.

2. Remove excess columns and calcuate other factors of interest.

3. Where are the processed cores from?

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4. Plotting by site and region

Below, the depth profile for organic matter (right) and inorganic mater (left) from each site is roughly plotted to compare the overall matter content. You will notice that site L06 is way different than the rest.

The core from L06 was loaded with chunky woody debris; in general, this site had a lot of woody debris at the surface of the sediment (see notes). The data are real but an outlier compared to the other sites. Here are two images of the sliced core from site L06:

For the sake of looking at regional patterns, I’ve removed Site L06 for further analysis.

Here the data are plotted again but grouped by sea otter region. In plots on the right, the sites are color coded to demonstrate the variance across sites (and in which sites); the mean values + standard error are shown on the left. The red lines represent the mean values for the entire length of the respective core.

Organic matter

Inorganic matter

OM:IM ratio

Looking at the means, it appears that OM and IM decrease as sea otters become more abundant in a region. The distribution across sites, however, may also be bimodal for the “Low” and “High” regions. The “Mid” region has questionable biomodality, instead the variance for few sites may be high. Let’s look at their distributions using density plots:

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For proper analysis, we need to decide how to deal with the bimodal distributions.

4. Other things? Plotting general patterns of mean core matter versus factors

Matter content * sea otter duration

I do have a question about the duration factor…there are only two year groups, 7 and 14. I don’t understand why the low sites are grouped in the 7-yr bin because some/most of those sites haven’t had sea otters at all; I would have expected a third “0-yr” category. I know that these spatial data are derived from elsewhere, but…

Matter content * sea otter index

I wouldn’t expect the buried OM and IM would interact with the sea otter index; burial relects a long/big temporal scale, where the sea otter index incorporates short-term data (e.g. cracked shells, pits).